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Thorough testing is necessary for developing and releasing a high-quality, well-functioning application. Test automation is a crucial component of application development because it creates an automated procedure allowing one or more test types to run without manual intervention. Additionally, it expedites the entire development process and guarantees that the newly created code performs exactly as expected without causing any regressions.
We will discuss Jest automation testing in this article, including a brief introduction to Jest, a list of its capabilities, and limitations, the primary factors that make Jest a well-liked testing tool, instructions for installing Jest, and more.
This framework is comprehensive because a large portion of its functionality is provided by internal resources rather than external tools. Jest is a comprehensive testing framework that has raised modern testing to a new level. It offers a blended package comprising an integrated assertion library, a built-in mocking library, and a test runner.
It is excellent for validation because it has tools that are well-managed, adequately documented, and organized in a way that makes developing tests easier. Due to the mocking and assertion libraries that are already integrated into it, tests may be executed more quickly and without fuss when they are run simultaneously. To speed up and simplify things, it runs previously failed tests first before rearranging the runs of the next tests, which are based on the lengthy test files.
This framework is primarily used for React testing by many large organizations, including Facebook, Twitter, Instagram, Pinterest, Spotify, and Airbnb.
After a brief introduction, let’s talk about some of Jest’s features.
Some of the features of Jest are-
Quick and effective – Jest’s framework is quick and safe. It rapidly executes all of the test cases without any lag time. Jest runs failed tests first and reorders test runs according to how long test files take, which makes it perform quickly and efficiently. Additionally, as tests are conducted concurrently, multiple configurations are tested at once.
Code coverage – Jest has excellent code coverage, which is the percentage of the code that is currently covered by unit tests. By utilizing the coverage command, Jest can generate code coverage. The coverage report can be produced with no further setup. This can be used to verify the test cases and forecast the number of additional test cases required to get greater coverage.
Strong Mocking support- Mocking is a strategy for separating different test subjects. This separation is accomplished by swapping out dependencies for objects that may inspect and manipulate the test subjects. Jest replaces dependencies with mock functions, which makes building mock functions quite simple.
Since the tests use a custom resolver for imports, it is simple to mock any object that is not within the scope of the test. Jest supports all varieties of mocking, including functional mocking, timer mocking, and simulating specific API calls.
Isolated working of all tests- Jest tests are executed in parallel to reduce runtime. The fundamental principle of isolation is to set up each test’s environment so that it will only consider executing one test at a time. This prevents any one test from interfering with another test’s operation or affecting the results of other tests. This characteristic makes the jest framework operate more quickly.
Support snapshot testing- Snapshot testing can be made possible by Jest. It enables checking the accuracy of huge objects. As a result, it is not necessary to create lengthy tests filled with assertions to determine whether each attribute is available and is of the appropriate type on an object. Jest will handle everything if you only create a snapshot.
Thorough API- Jest is well-known for having a comprehensive API that offers numerous specialized assertion types for particular needs. In addition, its great documentation makes it easy to start using it immediately.
Now that you are familiar with Jest’s characteristics, let’s examine its intended use.
Listed below are a few reasons for selecting Jest for test automation:
- Quick and easy, perfect for prototyping.
- Comes with an interactive mode that launches all affected tests automatically for the code changes made in the most recent commit.
- Provides a CLI tool to make it simple to control the tests;
- Provides .only and .skip syntax to test a single test or a set of tests. When troubleshooting particular tests, this function is useful.
- Enables the creation of code coverage reports by simply adding the parameter, coverage to the command line.
- Rich and valuable error reporting is provided during test execution.
- Offers great documentation, lots of examples, and a helpful community.
- A popular IDE like WebStorm does not support Jest.
- Jest offers fewer tools and library support than other comparable libraries.
- Jest snapshot testing is not appropriate for tasks that produce big, thousands-line snapshot files.
- Jest runs slower because of the auto-mocking feature.
Although installing Jest is not a particularly difficult procedure, there are a few requirements to meet beforehand. Here are some essential Jest libraries and packages that must be installed on the system to run Jest test scripts. So let’s examine them.
NodeJS and Node Package Manager (npm)- NodeJS can be installed either from the org website using the Windows Installer binary or using the npm manager. An open-source software library called Node Package Manager, or a command-line tool, is typically used to update, install, or remove different Node.js packages in web-based or mobile apps. It has about 8 lakhs code packages. Navigate the npm-command line tool and install the most recent version to start the npm command.
Selenium WebDriver- Selenium WebDriver is a web framework that enables the execution of cross-browser tests. It enables developers to create numerous test scripts in any programming language that fits them. Selenium WebDriver is used to automate the testing of any web-based or mobile application to see if it functions as intended or not.
When testing on a local Selenium Grid, Jest requires the Selenium WebDriver to be installed on the machine. The jest module is dependent on the Selenium web driver. The root directory contains the Jest module installation. The most recent version of Selenium WebDriver can be installed after setting up npm on the system.
Java SDK- The Java -SDK jest keyword can be used to execute commands from the command line. Make sure that the system has finished installing the Java Development Kit and has been configured with the Java environment before continuing with the installation of the JEST framework. This is because Jest is a Selenium test framework and Java is one of the most widely used languages for creating Selenium automation testing scripts.
The ‘-g’ flag, which may also be used with the npm command, can be used to install the jest module on a global scale. The’- g’ flag makes it simple to use the various Jest commands without first creating the package file for npm tests.
Jest is a Selenium test framework, and Java is the foundation of Selenium. LambdaTest is a cloud-based cross-browser testing platform that offers a Jest cloud grid and a cloud Selenium grid comprising more than 3000 real devices, browsers, and operating systems online for performing Jest and Selenium testing at scale.
The DevOps pipeline can also be effortlessly linked with LambdaTest. As a result, any CI/CD system may be used to create and run Jest test scenarios.
So use LambdaTest’s in-depth Jest tutorials to gain a deeper functional understanding of the framework and begin your Jest automation journey by executing your first Jest test script on the LambdaTest cloud.
In conclusion, Jest is one of the most widely used testing frameworks for online testing and is easy to use, reliable, and versatile. It comes with a wide range of test productivity tools, including minimal configuration, code coverage, comprehensive APIs, mocking capabilities, and more.